Nikola Tesla discovered the rotating magnetic field model. Marcel Deprez calculated that a rotating magnetic field could be produced by energizing mediums with polyphase systems (though this work may have been unkown to Telsa).

The Rotating magnetic fields are a consequence of the fundamental principles of electromagnetic fields in physics. Tesla visualized a iron rotor spinning rapidly in a rotating magnetic field produced by the interaction in a
polyhase system.

"On that fateful afternoon in February in Budapest in 1882, when he was given the vision of the rotating magnetic field, there had come with it an illumination that revealed to him the whole cosmos, in its infinite variations and its myriad of forms and manifestations, as a symphony of alternating currents. For him, the harmonies of the universe were played on a scale of electrical vibrations of a vast range in octaves. In one of the lower octaves was a single note, the 60-cycle-per-second alternating current, and in one of the higher octaves was visible light with its frequency of billions of cycles per second."

"Tesla had in mind a course of experimentation in which he would explore this region of electrical vibration between his alternating current and light waves. He would increase the frequency of the alternating current through the unknown intervening regions. If one note in a lower octave produced such a magnificent invention as the rotating magnetic field and the polyphase system, who could imagine the glorious possibilities that lay hidden in other notes in higher octaves? And there were thousands of octaves to be explored. He would construct an electrical harmonium by producing electrical vibrations in all frequencies, and study their characteristics. He would then, he hoped, be able to understand the motif of the cosmic symphony of electrical vibrations that pervaded the entire universe."

-- Prodigal Genius, pg. 84

Tesla in Strasburg, France built the induction motor which was experimental proof of the rotating magnetic field model.